FYVE1 Is Essential for Vacuole Biogenesis and Intracellular Trafficking in Arabidopsis

Abstract

The plant vacuole is a central organelle that is involved in various biological processes throughout the plant life cycle. Elucidating the mechanism of vacuole biogenesis and maintenance is thus the basis for our understanding of these processes. Proper formation of the vacuole has been shown to depend on the intracellular membrane trafficking pathway. Although several mutants with altered vacuole morphology have been characterized in the past, the molecular basis for plant vacuole biogenesis has yet to be fully elucidated. With the aim to identify key factors that are essential for vacuole biogenesis, we performed a forward genetics screen in Arabidopsis (Arabidopsis thaliana) and isolated mutants with altered vacuole morphology. The vacuolar fusion defective1 (vfd1) mutant shows seedling lethality and defects in central vacuole formation. VFD1 encodes a Fab1, YOTB, Vac1, and EEA1 (FYVE) domaincontaining protein, FYVE1, that has been implicated in intracellular trafficking. FYVE1 localizes on late endosomes and interacts with Src homology-3 domain-containing proteins. Mutants of FYVE1 are defective in ubiquitin-mediated protein degradation, vacuolar transport, and autophagy. Altogether, our results show that FYVE1 is essential for plant growth and development and place FYVE1 as a key regulator of intracellular trafficking and vacuole biogenesis.

ESCRT-III-Associated Protein ALIX Mediates High-Affinity Phosphate Transporter Trafficking to Maintain Phosphate Homeostasis in Arabidopsis

“…The latter include Arabidopsis thaliana ESCRT-I component ELCH (ortholog of Vps23p/TSG101 in yeast and mammals), ESCRT-III subunits VPS2 (Vps2p/CHMP2), VPS20 (Vps20p/CHMP6), VPS24 (Vps24p/CHMP3), SNF7 (Snf7/CHMP4), and ESCRT-III-associated SKD1 (Vps4p/SKD1), and CHMP1A and B (Did2p/CHMP1) proteins (Spitzer et al, 2006(Spitzer et al, , 2009Katsiarimpa et al, 2013;Cai et al, 2014). In addition, plant-specific ESCRT components have been identified, such as PROS, a positive regulator of SKD1, and FREE1, a FYVE domain-containing protein (also termed FYVE1) that interacts with ESCRT-I complexes at MVBs to allow sorting of ubiquitinated protein targets into ILVs (Gao et al, , 2015Reyes et al, 2014;Kolb et al, 2015). In most cases, complete loss of function of ESCRT components has deleterious effects in plants, leading to lethality at early developmental stages.…”

Arabidopsis ALIX is required for the endosomal localization of the deubiquitinating enzyme AMSH3

“…ESCRT-III components accumulate in aberrant late endosomal structures on inhibition of ESCRT-III disassembly by inactivation of the ATPases associated with diverse cellular activities (AAA)-ATPase suppressor of K+ transport growth defect 1(SKD1)/Vps4p (26,41,42). In Arabidopsis, the overexpression of ATPase-inactive SKD1(EQ) was shown to induce aggregation of endosomes (26,41) that were labeled with the late endosome marker ARA7, but not those labeled with the early endosome marker SYP41 or clathrin light chain (43). In accordance with the previously reported interaction with SNF7 (35) and its partially lateendosomal localization, GFP-ALIX accumulated in the SKD1 (EQ)-induced enlarged vesicular compartments together with the ESCRT-III subunit VPS2.1 and AMSH3-TagRFP (Fig.…”

Arabidopsis Class I Formin FH1 Relocates Between Membrane Compartments During Root Cell Ontogeny And Associates With Plasmodesmata

“…In such cells, FH1-GFP is found also in mobile membrane compartments within the cytoplasm, and in the root transition zone it transiently decorates the tonoplast at or around the stage when small vacuoles fuse to generate the large central vacuole (see e.g. Kolb et al 2015). The protein localization pattern was generally independent of the allelic status of FH1 and RDR6 (Supplementary data Table S9, Supplementary data Figure S10), a gene whose mutation prevents transgene silencing, but has also additional phenotypic effects (Peragine et al 2004).…”